Selecting base station at a multi-SIM communication device

ABSTRACT

Methods and devices to wirelessly connect to at least one base station at a multi-SIM device. The multi-SIM device comprises a plurality of SIM card interfaces and a plurality of RF units. The multi-SIM device first scans for base stations using as first RF unit, then observes the received signal quality using the first RF unit. The multi-SIM device may then transmit the data packets based in part on the received signal quality through at least one of the plurality of RF units.

TECHNICAL FIELD

The present invention relates in general to the field of computernetworks. More particularly, the present invention relates to methodsand systems for a multi-SIM communication device to establish wirelessconnections to at least one wireless communication network using atleast one RF unit.

BACKGROUND ART

Some of multi-SIM communication devices are capable of connecting to twoor more wireless communication networks. A multi-SIM communicationdevice may have one RF unit and thus only one SIM card is in use totransmit and receive data. As received signal quality of a base stationmay impact network performance of the multi-SIM communication devicesignificantly, it is preferred to connect to a base station that hasbetter received signal quality. Received signal quality with a basestation may change frequently as the multi-SIM communication device maymove and may also be affected by other wireless communication device.Further, the multi-SIM communication device may not be able to connectto a base station, which has better received signal quality, as themulti-SIM communication device may not be equipped with a SIM card thatis capable of establishing wireless connection with the base station.Therefore, the ability to keep observing received signal quality withother base stations, especially the base stations that the multi-SIMcommunication device can be connected to, even when a wirelessconnection has already been established becomes important.

DISCLOSURE OF INVENTION Summary

The present invention discloses methods and devices on selecting one ormore base stations by a multi-SIM communication device. The multi-SIMcommunication device comprises a plurality of SIM card interfaces, aplurality of RF units and at least one processing unit. The at least oneprocessing unit is capable of instructing one or more of the RF unit toscan for base stations for observing received signal quality.

According to one embodiment of the present invention, the receivedsignal quality is observed by a first RF unit and the first RF unittransmits data packets based in part on the received signal qualitythrough at least one of the RF units.

According to one embodiment of the present invention, the selection of afirst base station is based in part on the received signal quality whenit is above a threshold and establishing a wireless connection with thefirst base station using the second RF unit.

According to another embodiment of the present invention, the processingunit instructs the second RF unit to become available and establish awireless connection with the first base station if the second RF unit isunavailable and the second base station is below the threshold.

According to another embodiment of the present invention, a first tunneland a second tunnel are established through the wireless connectionsestablished with the first base station and the second base stationrespectively. The first tunnel and second tunnel can be aggregatedtogether to form an aggregated connection and data packets aretransmitted through the first and the second tunnels.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a block diagram of two wireless communication networksconfigured according to one of the embodiments of the present invention.

FIG. 2A is a block diagram of multi-SIM communication device with atleast two RF units configured according to one of the embodiments of thepresent invention.

FIG. 2B is a block diagram of multi-SIM communication device with a SIMcard interface selector configured according to one of the embodimentsof the present invention.

FIG. 2C is a block diagram of multi-SIM communication device with twoSIM cards and one RF unit configured according to one of the embodimentsof the present invention.

FIG. 2D is a block diagram of multi-SIM communication device with twoSIM cards and two RF units configured according to one of theembodiments of the present invention.

FIG. 3A is a flowchart of a process for transmitting data packets basedin part on observed received signal quality configured according to oneof the embodiments of the present invention.

FIG. 3B is a flowchart of a process for adjusting data transmissionperformance metric monitoring frequency based on observed receivedsignal quality configured according to one of the embodiments of thepresent invention.

FIG. 3C is a flowchart of a process for selecting a base station basedin part on observed received signal quality configured according to oneof the embodiments of the present invention.

FIG. 4A is a flowchart of a process for selecting a base station with athreshold based in part on observed received signal quality configuredaccording to one of the embodiments of the present invention.

FIG. 4B is a flowchart of a process to select an available RF unit toconnect to a base station based in part on observed received signalquality configured according to one of the embodiments of the presentinvention.

FIG. 5 is a flowchart of a process for event triggers configuredaccording to one of the embodiments of the present invention.

FIG. 6 is a flowchart of a process to select an operational SIM cardconfigured according to one of the embodiments of the present invention.

FIG. 7 is a block diagram of the SIM card interface selector configuredaccording to one of the embodiments of the present invention.

DETAILED DESCRIPTION

FIG. 1 illustrates two wireless communication networks, each of whichmay include a number of base stations and other network entities. Forsimplicity, FIG. 1 also illustrates four base stations 111, 112, 113 and114 and two network controllers 121 and 122. A base station may be afixed station that communicates with the multi-SIM communication devicesand may also be referred to as an access point, a node, an evolved node,etc. A base station may provide communication coverage for a particulargeographic area. The overall coverage area of a base station may bepartitioned into smaller areas, and each smaller area may be served by arespective base station subsystem. The term “cell” can refer to acoverage area of a base station and/or a base station subsystem servingthis coverage area, depending on the context in which the term is used.For illustration purpose only, a first wireless communication networkincludes base stations 111 and 112, and network controller 121; a secondwireless communication network includes base stations 113 and 114, andnetwork controller 122. The first wireless communication network and thesecond wireless communication network, for illustration purpose only,may be operated by a first network operator and a second networkoperator respectively.

Multiple Subscriber Identification Module (multi-SIM) device 101 may beone of many devices receiving wireless communication services by thefirst wireless communication network and the second wirelesscommunication network. Multi-SIM communication device 101 can be amobile phone, a router and access terminal (AT), a mobile station (MS),a wireless modem, a user equipment (UE), a subscriber unit, a station, adesktop computer, a laptop computer, a cordless phone, a wireless localloop (WLL) station, personal digital assistant (PDA), or any othernetworking nodes that have been developed to allow users to manage anduse more than one phone number via one device and via more than one SIMcard such as SIM card 201 a-c, SIM card 251 a-c, SIM card 291 a and 291b, and SIM card 262 a and 262 b.This invention may cover physical SIMcards of any size, as well as soft-SIM solutions or virtual-SIMsolutions.

Multi-SIM communication device 101 may be stationary or mobile and maycommunicate with a base station via the downlink and uplink. Thedownlink (or forward link) refers to the communication link from thebase station to multi-SIM communication device 101, and the uplink (orreverse link) refers to the communication link from multi-SIMcommunication device 101 to the base station.

The techniques described herein may be used for various wirelesscommunication networks such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA andother networks. The terms “network” and “system” are often usedinterchangeably. A CDMA network may implement a radio technology such asUniversal Terrestrial Radio Access (UTRA), CDMA2000, etc. UTRA includesWideband CDMA (WCDMA) and other variants of CDMA. CDMA 2000 coversIS-2000, IS-95 and IS-856 standards. A TDMA network may implement aradio technology such as Global System for Mobile Communications (GSM).An OFDMA network may implement a radio technology such as Evolved UTRA(E-UTRA), Ultra Mobile Broadband (UMB), IEEE 802.11 (Wi-Fi), IEEE 802.16(WiMAX), IEEE 802.20, Flash-OFDM, etc. UTRA and EUTRA are part ofUniversal Mobile Telecommunication System (UMTS). 3GPP Long TermEvolution (LTE) is a UMTS that uses E-UTRA, which employs OFDMA on thedownlink and SC-FDMA on the uplink. UTRA, E-UTRA, UMTS, LTE and GSM aredescribed in documents from an organization named “3rd GenerationPartnership Project” (3GPP). CDMA 2000 and UMB are described indocuments from an organization named “3rd Generation Partnership Project2” (3GPP2).

FIG. 2A illustrates one of embodiments according to the presentinvention. Multi-SIM communication device 101 a has at least two radiounits. There can be more number of SIM card interfaces than the numberof radio frequency (RF) units. RF units, such as RF units 221 a and 221b, are connected to embedded/external antennas respectively. A RF unitcan be connected to one or more SIM card interface. An external deviceconnected to multi-SIM communication device 101 may also house RF unitsand SIM card interfaces, and thus RF units and SIM card interfaces arenot housed by multi-SIM communication device 101. A SIM card can beplaced in the external device. For example, the external device is aUniversal Serial Bus (USB) 3GPP modem. In another example, the externaldevice is a Universal Serial Bus (USB) LTE modem. Multi-SIM device 101is capable of connecting to one or more external devices. For example, aUSB modem is connected to the USB interface of multi-SIM device 101.According to one of the embodiments of the present invention, the RFunit or the multi-SIM device to be reset in order for it to be able touse another SIM card. One of the methods to reset to RF unit is topower-cycle the RF unit. For example RF unit 221 a is connected to SIMcard interface 211 a only and RF unit 221 b is connected to SIM cardinterfaces 211 b and 211 c. When RF unit 221 b is using SIM card 201 b,RF unit 221 b cannot use SIM card 201 c. Processing unit 231, forexample, can instruct RF unit 221 b to use SIM cards 201 b and 201 c intandem through SIM card interfaces 211 b and 211 c respectively. Inanother example, processing unit 231 can instruct RF unit 221 b to useonly one of SIM cards 201 b and 201 c until an event that triggersprocessing unit 231 to instruct RF unit 221 b to use another SIM card.

Memory, such as 234, 285, 297 and 266 may represent one or more devicesfor storing data in a volatile state. These devices may include randomaccess memory (RAM), magnetic RAM, core memory and/or other machinereadable mediums for storing volatile data.

A storage unit, such as storage unit 232, 282, 296 and 267 may representone or more devices for storing data, including read only memory (ROM),magnetic disk storage mediums, optical storage mediums, flash memorydevices and/or other machine readable mediums for storing information.

The term “machine-readable medium” includes, but is not limited toportable or fixed storage devices, optical storage devices, wirelesschannels and various other mediums capable of storing, containing orcarrying instruction(s) and/or data. A machine readable medium can berealized by virtualization, and can be a virtual machine readable mediumincluding a virtual machine readable medium in a cloud-based instance.Furthermore, embodiments may be implemented by hardware, software,firmware, middleware, microcode, hardware description languages, or anycombination thereof. When implemented in software, firmware, middlewareor microcode, the program code or code segments to perform the necessarytasks may be stored in a machine readable medium such as storage medium.

A processing unit, such as processing unit 231, 281, 295 and 265 mayperform the necessary tasks. A code segment may represent a procedure, afunction, a subprogram, a program, a routine, a subroutine, a module, asoftware package, a class, or any combination of instructions, datastructures, or program statements. A code segment may be coupled toanother code segment or a hardware circuit by passing and/or receivinginformation, data arguments, parameters, or memory contents.Information, arguments, parameters, data, etc. may be passed, forwarded,or transmitted via any suitable means including memory sharing, messagepassing, token passing, network transmission, etc. A processing unit(s)can be realized by virtualization, and can be a virtual processingunit(s) including a virtual processing unit in a cloud-based instance.

A SIM card interface, such as SIM card interfaces 261 a-261 c, 211 a-211c, 292 a and 292 b, and 263 a and 263 b, is used to access and writeinformation to and from a SIM card. There are many SIM card interfacesavailable from different manufacturers. Some of the SIM card interfacesprovide functions of power supply, card reset signal, card clock signaland data exchange. A data exchange can be performed between the SIM cardand processing unit 231, SIM Card Interface Selector 284 or RF units221. Some of SIM card interfaces can only be connected with one SIM cardwhile some can be connected to a plurality of SIM cards. Examples of SIMcard interface include ON Semiconductor's NCN6804 and NCN8024, andFairchild Semiconductor's FXLP4555.

A network interface, such as network interface 233 a, 233 b, 283 a, 283b, 294 a, 294 b, 268 a and 268 b in multi-SIM communication device 101,may be an Ethernet interface, a frame relay interface, a fibre opticinterface, a cable interface, a DSL interface, a token ring interface, aserial bus interface, an universal serial bus (USB) interface, Firewireinterface, Peripheral Component Interconnect (PCI) interface, etc. Theremay be more than one network interface in multi-SIM communication device101. A network interface may be used as a local area network (LAN)interface or a wide area network (WAN) interface.

System bus such as 240, 241, 242 and 243 allows multi-SIM communicationdevice 101 to have increased modularity. For example, System bus 240couples processing unit 231 to storage unit 232, RF unit 221 a, networkinterface 233 a, network interface 233 b, and RF unit 221 b. System buscan be any of several types of bus structures including a memory bus, aperipheral bus, and a local bus using any of a variety of busarchitectures.

Multi-SIM communication device 101 a may be within the coverage ofmultiple base stations. More than one of base stations may be selectedfrom these multiple base stations to serve multi-SIM communicationdevice 101 a. The selection of one or more serving base stations may bereferred to as server selection. The selection of base station to servermulti-SIM communication device 101 a (server selection) may be initiatedby multi-SIM communication device 101 a, by a base station, and/or bythe wireless communication network. Multi-SIM communication device 101 amay request to be served by a base station. The base station may acceptor reject the request. The wireless communication network may alsoaccept or reject the request. A base station or wireless communicationnetwork may consider one or more factors to determine whether to acceptor reject the request, including network capacity, processing capacity,number of concurrent connections, and etc.

In one example, when the server selection is initiated by a basestation, multi-SIM communication device 101 a may or may not be able toreject the server selection if multi-SIM communication device 101 adecides to connect to the same network. Then base station 111 or basestation 112 may instruct multi-SIM communication device 101 a to connectto base station 111 when multi-SIM communication device 101 a hasalready been connected with base station 112. If multi-SIM communicationdevice 101 a refuses to connect to base station 111, multi-SIMcommunication device 101 a will not be able to connect to the firstwireless communication network through base station 112 as base station112 will later disconnect with multi-SIM communication device 101 a.

In one example, multi-SIM communication device 101 a may try to connectto a particular base station, such as base station 112. Multi-SIMcommunication device may send the request to the first wirelesscommunication. If the request is authorized, then multi-SIMcommunication device can then connect to base station 111.

A base station is a qualified base station if the received signalquality from the base station is above a threshold and multi-SIMcommunication device 101 a can be authorized to connect to the basestation by using information from one of SIM cards 201. In one variant,if a base station can only be connected through a RF unit that iscapable of establishing a wireless connection with a LTE network, thebase station can only be a qualified base station when using the RFunit. The base station may not be a qualified base station when usinganother RF unit, which is not capable of establishing a wirelessconnection with a LTE network.

When processing unit 231 determines to establish a wireless connectionwith a base station, the base station is the Selected Base Station. TheSelected Base Station is connected using one of RF units 221 usingauthentication information retrieved from a corresponding SIM card. Itis possible that a Selected Base Station cannot be connected to becauseof many reasons, including lack of capacity at the Selected BaseStation, refusal by the Selected Base Station, etc.

A RF unit is available when it has not established any wirelessconnection. If a RF unit is not available, the RF unit cannot be used toestablish an additional wireless connection. In one example, in order tohave a RF unit that is originally unavailable to become available, theRF unit may need to disconnect established wireless connection beforeestablishing another wireless connection.

FIG. 3A illustrates one of the embodiments according to the presentinvention. At step 301, processing unit 231 instructs one of RF units221 (Scanning RF Unit) to scan for base stations that multi-SIMcommunication device 101 a can be connected to. Although multi-SIMcommunication device 101 a may find many base stations during the scan,multi-SIM communication device 101 a only observes received signalquality for those base stations that multi-SIM communication device 101a can connect to. Multi-SIM communication device 101 a can only connectto base stations operated by network operators that authorize SIM cards201 to connect to. For example, use of SIM cards 201 a, 201 b and 201 callows multi-SIM communication device 101 a to connect to a base stationof a wireless communication network operated by a first networkoperator, a second network operator and a third network operatorrespectively. As base stations 111 and 112 are operated by the firstnetwork operator and base stations 113 and 114 are operated by thesecond network operator, multi-SIM communication device 101 a canconnect to base stations 111-114 by using SIM cards 201 a or 201 b. Inanother example, a plurality of SIM cards 201 may be used by processingunit 231 to enable multi-SIM communication device 101 a to establishmore than one wireless connection with a base station.

When processing unit 231 selects SIM cards 211 b or 221 c for RF unit221 b for use, processing unit 231 instructs RF unit 221 b to select SIMcard interface 211 b or 211 c for SIM cards 211 b or 211 c respectivelyaccording to the instruction sent by processing unit 231. Alternatively,RF unit 221 b does not connect to SIM card interfaces 211 b and 211 cdirectly. Instead, SIM card interfaces 211 b and 211 c are connected tobus 240. In such case, SIM card information is retrieved from SIM cardinterfaces 211 b and/or 211 c and then sent to RF unit 221 b.Alternatively, there could be a SIM card interface selector, like theone illustrated in FIG. 7 for the embodiment illustrated in FIG. 2B,connects SIM card interfaces 211 b and 211 c to RF unit 221 b and iscontrolled by processing unit 231. Examples of a SIM card interfaceselector for two SIM card interfaces include TXS02326 Dual-Supply 2:1SIM Card Multiplexer/Translator supplied by Texas Instruments andLTC4557 Dual SIM/Smart Card Power Supply and Interface supplied byLinear Technology.

At step 302, the Scanning RF Unit observes received signal quality ofthe base stations 111, 112, 113 and 114. Both RF units 221 a and 221 bcan be the Scanning RF Unit. For example, RF unit 221 b is the ScanningRF Unit, while RF unit 221 a is not Scanning RF Unit and will notperform received signal quality observation. In one example, RF unit 221a is a Scanning RF Unit for a period of time and then not being theScanning RF Unit for another period of time. Therefore, RF unit 221 amay be able to perform other non-received signal quality observationfunctions when RF unit 221 a is not a Scanning RF Unit. It is preferredthat only one of RF units 221 a and 221 b is a Scanning RF Unit at anyparticular moment as the benefits of more than one RF units to observereceived signal quality is limited. As some RF units may not be able toprovide data communication functions when being a Scanning RF Unit, theshorter period of time a RF unit is a Scanning RF, the more time the RFunit can provide data communication functions. In one variant, asdifferent RF units are used as Scanning RF Units, it is possible thatobserved received signal qualities associated with a base station aredifferent. Processing unit 231 may average the observed received signalqualities or choose the most recent observed received signal qualitybefore further processing.

Steps 301 and 302 may be performed all the time, periodically and/orupon an instruction received by processing unit 231. The more frequentstep 301 is performed, the sooner multi-SIM communication device 101 amay be able to connect to a base station that has better received signalquality and may result in higher data throughput. If a RF unit is notable to perform steps 301 and/or step 302 while being wirelesslyconnected with a base station, step 301 and/or step 302 should be notperformed. If a RF unit is not able to perform scanning whiletransmitting or receiving data from the wireless connected base station,step 301 and/or step 302 should be performed less frequently in order toavoid interruptions to data transmission and receiving.

In one variant, the frequency of performing steps 301 and 302 can bedifferent. The frequency of performing step 302 is preferred to beperformed more frequently than of step 301. The number of base stationsavailable to be connected does not change significantly if multi-SIMcommunication device 101 a does not move much. However, received signalquality may change even if multi-SIM communication device 101 a isstationary. After step 301 is performed, step 302 may be performed anumber of times before step 301 is performed again. In one example, step301 is performed every thirty seconds and step 302 is performed tentimes every thirty seconds.

At step 303, processing unit 231 transmits data packets based in part onobserved received signal quality after observing received signal qualityof base stations 111-114. The Scanning RF Unit may be able to observereceived signal quality of base stations other than base stations111-114. It is preferred that processing unit 231 does not transmit datapackets based in part on observed received signal quality of basestations other than base stations 111-114 because multi-SIMcommunication device 101 a cannot connect to base stations other thanbase stations 111-114. For example, when processing unit 231 determinesthat received signal quality with base station 111 is the best among thereceived signal qualities with base stations 111-114, processing unit231 transmits more data packets through base station 111 than throughbase stations 112, 113 and 114. In another example, when processing unit231 determines that received signal quality with base station 111 andbase station 113 are the best among the received signal qualities withbase stations 111-114, procession unit 231 transmits data packetsthrough base stations 111 and 113. In one variant, as RF unit 221 a canonly connect to one of base stations 111 and 112 and RF unit 221 bcannot connect to any of base stations 111 and 112, multi-SIMcommunication device 101 a can only connect one of base stations 111 and112 through SIM card 201 a and RF unit 221 a. Therefore, even ifreceived signal qualities with base stations 111 and 112 are better thanreceived signal qualities with base stations 113 and 114, processingunit 231 will transmit data packets through RF units 221 a with one ofbase stations 111 and 112 and through RF unit 221 b with one of basestations 113 and 114.

FIG. 3B illustrates one of the embodiments according to the presentinvention. The difference between the processes in FIG. 3B and FIG. 3Ais that step 303 is replaced by step 313. At step 313, processing unit231 adjusts data transmission performance metric monitoring frequencybased in part on observed received signal quality. As received signalquality of a wireless connection changes and if a RF unit istransmitting and/or receiving through the wireless connection, datatransmission performance metric may be affected by the received signalquality change. When the received signal quality is good, there is lessneed to monitor the data transmission performance metric frequently. Onthe other hand, when the received signal quality is below a threshold,the data transmission performance metric monitoring should be performedmore frequently as it is possible that the wireless connection canbecome unstable quickly. In one example, RF unit 221 a is the ScanningRF Unit and RF unit 221 b is transmitting data packets through awireless connection established between RF unit 221 b and base station114. When RF unit 221 a has observed the received signal quality of thewireless connection between RF unit 221 b and base station 114 hasdropped below a threshold, processing unit 231 monitors datatransmission performance metric for data packets transmitted through RFunit 221 b more frequently. When the received signal quality of thewireless connection between RF unit 221 b and base station 114 hasimproved and is above the threshold, processing unit 231 monitors datatransmission performance metric for data packets transmitted through RFunit 221 b at a regular frequency. When processing unit 231 has found awireless connection is unstable, it stops transmitting data packetsthrough the wireless connection. In one variant, if the wirelessconnection with base station 114 is unstable, processing unit 231 thendisconnects the wireless connection with base station 114 and tries toestablish another wireless connection with another base station.

FIG. 3C illustrates one of the embodiments according to the presentinvention. The difference between the processes in FIG. 3B and FIG. 3Ais that step 303 is replaced by steps 323 and 324. At step 323,processing unit 231 selects a base station (Selected Base Station) basedin part on observed received signal quality. The better the observedreceived signal quality with a base station being observed, the morelikely the base station is selected. The Selected Base Station shouldalso be a base station that can be connected by one of RF units 221. Ifreceived signal quality with a base station is highest among allreceived signal qualities observed but the base station cannot beconnected through any of RF units 221, the base station will not beselected by processing unit 231 and cannot be a Selected Base Station.In one variant, in order for processing unit 231 to select a basestation to be the Selected Base Station, the received signal qualitywith the base station has to be higher than a threshold.

At step 324, processing unit 231 instructs one of RF units 221 toconnect to the Selected Base Station if processing unit 231 decides so.For example, if the Selected Base Station is base station 114 and onlyRF unit 221 b can be used to connect to base station 114. Processingunit 231 will then instruct RF unit 221 b to connect to base station114. In one variant, processing unit 231 will only instruct RF unit 221b to connect to base station 114 if RF unit 221 b has not establishedany wireless connection with another base station in order to avoidbreaking established communication. In one variant, processing unit 231will only instruct RF unit 221 b to connect to base station 114 if RFunit 221 b has established a wireless connection with another basestation but the received signal quality with the another base station islower than a threshold. The received signal quality with the anotherbase station is observed at step 302. In one variant, processing unit231 will only instruct RF unit 221 b to connect to base station 114 ifthe received signal quality with RF unit 221 b is above a threshold.

In one variant, steps 301 and 302 are being performed continuously aftermulti-SIM communication device 101 a is powered up therefore processingunit 231 can continuously find base stations that are qualified to bethe Selected Base Station.

FIG. 2B illustrates one of the embodiments according to the presentinvention. Multi-SIM communication device 101 b has at least two radiounits. There can be more number of SIM card interfaces than the numberof radio frequency (RF) units. RF units, such as 271 a and 271 b, areconnected to embedded/external antennas respectively. SIM card interfaceselector 284 provides access for RF units 271 to connect to SIM cardinterfaces 261. Instructed by processing unit 281, one or more SIM cardinterfaces 261 may be selected by SIM card interface selector 284 toestablish wireless connections using RF units 271. In this example, SIMcard interface selector 284 may select SIM card interface 261 a, 261 bor 261 c for use by RF unit 271 b. Furthermore, SIM card interfaceselector 284 may select SIM card interface 261 a, 261 b or 261 c for useby RF unit 271 a. Therefore, SIM card interface selector 284 is capableof allowing any RF unit 271 to use any SIM card 251 by usingmultiplexing technique known to those skilled in the art. Processingunit 281 instructs RF unit 271 b to perform other tasks when RF unit isnot used to establish a wireless connection. Other tasks may includeserving as a Scanning RF Unit to scan for base stations or to establisha wireless connection.

In one example, SIM card interface selector 284 is a multiplexer thatallows RF unit 271 a and RF unit 271 b connects to any of SIM cardinterfaces 261 a, 261 b and 261 c as illustrated in FIG. 7. Preferably,when a SIM card interface is already connected to one of RF units 271,the other of RF unit 271 cannot connect to the same SIM card interfaceas most wireless communication networks only allow one SIM card toestablish one wireless connection at any time. However, there is nolimitation that one SIM card interface must be connected to one RF unitonly. There is no limitation on the number of SIM card interfaces that aSIM card interface selector can connect to. Similarly, there is nolimitation on the number of RF units that a SIM card interface selectorcan connect to.

In another embodiment, multi-SIM communication device 101 b performsaccording to the steps illustrated in FIG. 3C. At step 301, processingunit 281 instructs one of RF units 271 (Scanning RF Unit) to scan forbase stations that multi-SIM communication device 101 b can be connectedto. Although multi-SIM communication device 101 b may find many basestations during the scan, multi-SIM communication device 101 b onlyobserves received signal quality for those base stations that multi-SIMcommunication device 101 b can connect to or may observe no signal atall.

Multi-SIM communication device 101 b can only connect to base stationsoperated by network operators that authorize SIM cards 251 to connectto. For example, use of SIM cards 251 a, 251 b and 251 c allowsmulti-SIM communication device 101 b to connect to a base station of awireless communication networks operated by a first network operator, asecond network operator and a third network operator respectively. Asbase stations 111 and 112 are operated by the first network operator andbase stations 113 and 114 are operated by the second network operator,multi-SIM communication device 101 b can connect to base stations111-114 by using SIM cards 251 a and 251 b. Multi-SIM communicationdevice 101 b may not be able to connect to the third wirelesscommunication network using SIM card 251 c when there are no basestations providing wireless communications service from the thirdwireless communication network.

In one example, a plurality of SIM cards 251 may be selected by SIM CardInterface Selector 284, and used by processing unit 281 to enablemulti-SIM communication device 101 b to establish more than one wirelessconnection with a base station. The selection may also be performed byprocessing unit 281. For example, processing unit 281 may instruct RFunit 271 a and RF unit 271 b to use SIM card 251 a and SIM card 251 b toestablish wireless connections with base station 111 and base station113 respectively. Processing unit 281 instructs SIM card interfaceselector 281 to provide RF units 271 access to SIM card interface 261.This may allow multi-SIM communication device 101 b to have at least onewireless connection established with a wireless communication network.For example, when multi-SIM communication device 101 b is out ofcoverage of the second wireless communication network, multi-SIMcommunication device 101 b can stay connected with the first wirelesscommunication network using SIM card 251 b. In one variant, since SIMcard 251 b is operating without the coverage of its authorizedcommunication network which is the second wireless communicationnetwork, multi-SIM communication device 101 b may be configured to beoperating on a roaming network and may incur network roaming charges.

At step 302, the Scanning RF Unit observes received signal quality ofthe base stations 111, 112, 113 and 114. Both RF units 271 a and 271 bcan be the Scanning RF Unit. For example, RF unit 271 b is the ScanningRF Unit while RF unit 271 a is not Scanning RF Unit and will not performreceived signal quality observation. In one example, RF unit 271 a is aScanning RF Unit for a period of time and then is not for another periodof time. Therefore, RF unit 271 a may be able to perform othernon-received signal quality observation functions when RF unit 271 a isnot a Scanning RF Unit. It is preferred that only one of RF units 271 aand 271 b is a Scanning RF Unit at any particular moment as the benefitsof more than one RF units to observe received signal quality is limited.As some RF units may not be able to provide data communication functionswhen being a Scanning RF Unit, the shorter period of time a RF unit is aScanning RF Unit, the more time the RF unit can provide datacommunication functions. In one variant, as different RF units are usedas Scanning RF Units, it is possible that observed received signalqualities associated with a base station are different. Processing unit281 may average the observed received signal qualities or choose themost recent observed received signal quality before further processing.

At step 323, processing unit 281 selects a base station (Selected BaseStation) based in part on observed received signal quality. The betterthe observed received signal quality with a base station being observed,the more likely the base station is selected. The base station may alsobe selected by processing unit 281 based in part on policies oralgorithms or centralized management methods. The Selected Base Stationshould also be a base station that can be connected by one of RF units271. If received signal quality with a base station is highest among allreceived signal qualities observed but the base station cannot beconnected through any of RF units 271, the base station will not beselected by processing unit 281 and cannot be a Selected Base Station.In one variant, in order for processing unit 281 to select a basestation to be the Selected Base station, the received signal qualitywith the base station has to be higher than a threshold.

At step 324, processing unit 281 through SIM card interface selector284, instructs RF units 271 to use SIM cards 251 through at least one ofSIM card interface 261 to connect to the Selected Base Station.Alternatively, processing unit 281 instructs SIM card interface selector284 to provide information retrieved from one of SIM cards 251 to one ofRF units 271 and processing unit 281 also instructs the one of RF units271 to connect to the Selected Base Station based in part on theinformation retrieved at the same time if processing unit 281 decidesso. For example, the Selected Base Station is base station 114 and anyRF unit 271 can be used to connect to base station 114 because any of RFunit 271 can use any of the SIM cards 251.

In one example, base stations 113 and 114 belong to the second wirelesscommunication network and are operated by the second network operator.Base station 114 is the Selected Base Station based in part on thethreshold. Processing unit 281 also determines RF unit 271 b will beused to establish a wireless connection with Selected Base Station 114.Processing unit 281 then instructs SIM card interface selector 284 toselect SIM card interface 261 b to connect with a SIM card that has thecorresponding authentication information, in this example, SIM card 251b.

In one variant, processing unit 281 will only instruct SIM cardinterface selector 284 to select SIM card 251 b to be served by RF unit271 b to connect to base station 114 if RF unit 271 b has established awireless connection with another base station and the received signalquality is below the threshold. The received signal quality with theanother base station is observed at step 302. This ensures thatmulti-SIM communication device 101 b establishes wireless connectionswith qualified base stations that have observed signal qualities abovethe threshold.

FIG. 4A illustrates one of the embodiments according to the presentinvention. At step 401, processing unit has already observed receivedsignal quality of the base stations 111, 112, 113 and 114 through aScanning RF Unit. At step 430, processing unit 231 selects a basestation from the list of base stations that are qualified to be theSelected Base Station based in part on observed received signal quality.A base station is qualified if the received signal quality with the basestation is higher than a threshold. When there is more than one basestation qualified, processing unit 231 selects one of the base stationsto be Selected Base Station. The selection may be performed according toreceived signal quality, predefined priority, preferences, price andetc. In case after step 437, the Selected Base Station cannot be used,processing unit 231 will select another base station from the qualifiedbase stations. For illustration purpose, base station 114 is theSelected Base Station. At step 431, processing unit 231 determineswhether a RF unit is available to connect to the Selected Base Station.When there is no RF unit available to connect to the Selected BaseStation, processing unit 231 determines whether any of received signalquality with each connected base station, which has established awireless connection with multi-SIM communication device 101 a, is belowa threshold at step 432. In an example, for illustration purpose, whenRF units 221 a and 221 b have already established wireless connectionswith base stations 111 and 113 respectively, there is no RF unitavailable at step 431. Then processing unit 231 determines whether thereceived signal quality of the wireless connection established by RFunit 221 a and base station 111 or the received signal quality of thewireless connection established by RF unit 221 b and base station 113 isbelow than a threshold at step 432. If none of the received signalquality is below the threshold, the Selected Base Station is not used toestablish a wireless connection and the process stops at step 402. Ifone of the received signal qualities with the base stations is below thethreshold, for example, the received signal quality of wirelessconnection established by RF unit 221 b and base station 113 is belowthe threshold, step 434 is performed.

For illustration purpose, when the received signal quality of wirelessconnection established by RF unit 221 b and base station 113 is lowerthan the threshold, then at step 434, processing unit 231 instructs RFunit 221 b to terminate the wireless connection with base station 113.The termination frees resources at RF unit 221 b and allows RF unit 221b to establish a new wireless connection. At step 435, processing unit231 instructs RF unit 221 b to connect to the Selected Base Station. Atstep 436, processing unit 231 checks whether RF unit 221 b is able toestablish a wireless connection with the Selected Base Station which isbase station 114. If RF unit 221 b has successfully established awireless connection with base station 114, processing unit 231 can thentransmitting and receiving IP packets through RF unit 221 b and basestation 114 at step 438. Those who are skilled in the arts wouldappreciate that IP packets can be transmitted using transmission controlprotocol (TCP), user datagram protocol (UDP), or other protocols. If RFunit 221 b cannot establish a wireless connection with base station 114,processing unit 231 checks if there is another qualified base station tobe the Selected Base Station at step 437. If there is at least one morequalified base station, step 430 is performed to select the at least onemore qualified base station. If there is no more qualified base station,the process stops at step 402. In one variant, when there is no morebase station qualified to be connected to at step 437, processing unit231 will attempt to connect to the base station that was disconnectedfrom at step 434. This allows processing unit 231 to try to return tohave the same number of wireless connections. In one variant, if a RFunit is capable of establishing a wireless connection withoutdisconnection another wireless connection that has already beenestablished, steps 431, 432 and 434 will then be performed after step438 in order not to terminate an established wireless connection tooearly.

In one variant, step 430 is preferred to be performed after step 431 orstep 434 as shown in FIG. 4B. As there is no RF unit available and noneof the received signal quality for established wireless connection isworse than a threshold, step 434 is avoided in order to reduce theprobability of interrupting ongoing data communications and step 430 isalso not performed in order to reduce computing resources.

FIG. 4B illustrates one of the embodiments according to the presentinvention. At step 401, processing unit has already observed receivedsignal quality of the base stations 111, 112, 113 and 114 through aScanning RF Unit.

At step 431, processing unit 281 determines whether any RF unit isavailable to connect to the Selected Base Station. When there is no RFunit available to connect to the Selected Base Station, processing unit281 determines whether any of received signal quality with eachconnected base station, which has established a wireless connection withmulti-SIM communication device 101 b, is below a threshold at step 432.

In an example, for illustration purpose, when RF units 271 a and 271 bhave already established wireless connections with base stations 111 and113 respectively, there is no RF unit available at step 431. Thenprocessing unit 281 determines whether the received signal quality ofthe wireless connection established by RF unit 271 a and base station111 or the received signal quality of the wireless connectionestablished by RF unit 271 b and base station 113 is below a thresholdat step 432. If none of the received signal quality is below thethreshold, the selected base station is not used to establish a wirelessconnection and the process stops at step 402. If one of the receivedsignal qualities with the base stations is below the threshold, forexample, the received signal quality of wireless connection establishedby RF unit 271 b and base station 113 is below the threshold, step 434is performed.

At step 434, processing unit 281 instructs RF unit 271 b to disconnectfrom base station 113 so that RF unit 271 b can become an available RFunit.

At step 430, processing unit 281 selects a base station from the list ofbase stations that are qualified to be the Selected Base Station basedin part on observed received signal quality. When there are more thanone base stations qualified, processing unit 281 selects one of the basestations to be Selected Base Station. The selection may be performedaccording to received signal quality, predefined priority, preferences,price etc. At step 430, base station 114 is the selected base stationafter processing unit 281 determines the observed signal quality of basestation 114 to be above the threshold. In one variant, at step 436 theSelected Base Station is found not capable of being used and there is nomore qualified base station at step 437, step 430 restarts andprocessing unit 281 will select another base station from the qualifiedbase stations. This is to try to ensure multi-SIM communication device101 b always has at least one established wireless connection with thequalified base station that has the observed received signal qualityabove the threshold. In one variant, if there is no base station thatcan offer wireless communication service with observed received signalquality above the threshold, multi-SIM communication device 101 b mayattempt to establish wireless connections with a base station with thehighest observed received signal quality.

At step 435, SIM card 251 b is connected to SIM card interface 261 b andis authorized to connect with the second wireless communication networkand base station 114. Processing unit 281 instructs SIM card interfaceselector 284 to select SIM card interface 261 b, which is connected toSIM card 251 b, to establish a wireless connection with the SelectedBase Station 114 through RF unit 271 b.

At step 436, processing unit 281 instructs SIM card interface selector284 to select a SIM card interface 261, then verifies whether RF unit271 is able to establish a wireless connection with a Selected BaseStation. If RF unit 271 successfully establishes a wireless connection abase station, processing unit 281 can then transmit and receive IPpackets through RF unit 271 and the base station at step 438. If RF unit271 b successfully establishes a wireless connection with base station114, processing unit 281 then transmits and receives IP packets throughRF unit 271 b and the base station 114 at step 438. If RF unit 271 bcannot establish a wireless connection with base station 114, processingunit 281 checks if there is another qualified base station to be theSelected Base Station at step 437. If there is at least one morequalified base station, step 430 is performed to select the at least onemore qualified base station. If there is no more qualified base station,the process stops at step 402. In one variant, when there is no morebase station qualified to be connected to at step 437, processing unit281 may instruct RF unit 271 to connect to the base station that wasdisconnected from at step 434. This allows multi-SIM communicationdevice 101 b to try to have at least one established wireless connectionwith the qualified base station that has the observed signal qualityabove the threshold. In one variant, if a RF unit is capable ofestablishing a wireless connection without disconnecting anotherwireless connection that has already been established, steps 431, 432and 434 will then be performed after step 438 in order not to terminatethe established wireless connection too early.

In one variant, step 430 is preferred to be performed after step 431 orstep 434. As there is no RF unit available and none of the receivedsignal quality for established wireless connection is worse than athreshold, step 434 is avoided in order to reduce the probability ofinterrupting ongoing data communications and step 430 is also notperformed in order to reduce computing resources.

FIG. 1 also illustrates a network environment that a multi-SIM iscapable of transmitting and receiving data packets through an aggregatedtunnel according to one of the embodiments of the present invention.Multi-SIM communication device 101, such as multi-SIM communicationdevice 101 a, 101 b and 101 d, that has more than one RF unit, and hasestablished at least two wireless connections between at least two RFunits and at least one base station. Multi-SIM communication device 101c cannot be used for this embodiment as it only has one RF unit 293 aunless RF unit 293 a is able to establish more than one wirelessconnection. An aggregated tunnel is then established through the atleast two wireless connections. Within each of the established wirelessconnections, a tunnel is established between multi-SIM communicationdevice 101 and network node 119 for transmitting and receiving datapackets. The data packets may be encapsulated by using a tunnelingprotocol packet. The aggregated tunnel may be an aggregated virtualprivate network (VPN) connection. Multi-SIM communication device 101 andnetwork node 119 may first negotiate tunnel configuration variables,such as address assignments, compression parameters and encryptionmethods before transmitting and receiving data packets. Multi-SIMcommunication device 101 transmits the encapsulated data packets acrossinterconnected networks 117. Network node 119 may decapsulate theencapsulated data packets to retrieve the data packets upon receivingthe encapsulated data packets.

In one example, multi-SIM communication device 101 establishes a tunnelusing RF unit 221 a with base station 111 on the first wirelesscommunication network and another tunnel with RF unit 221 b with basestation 113 on the second wireless communication network. For thepurpose of illustration, the tunnel established using RF unit 221 a isreferred to as tunnel A and the tunnel established using RF unit 221 bis referred to as tunnel B. Tunnel A and tunnel B together are used toform an aggregated tunnel.

When the established wireless connections between multi-SIMcommunication device 101 and both base station 111 and 113 are stable,multi-SIM communication device 101 are able to transmit data packetsthrough the aggregated tunnel using both tunnel A and tunnel B withoutmany packet drops. When the established wireless connection betweenmulti-SIM communication device 101 and base station 111 is stable butthe established wireless connection between multi-SIM communicationdevice 101 a and base station 113 is unstable, tunnel B may becomebroken. Multi-SIM communication device 101 then transmits data packetsthrough the aggregated tunnel using tunnel A and stops transmitting datapackets through tunnel B. In one variant, after the wireless connectionbetween multi-SIM communication device 101 a and base station 113 isstable again and tunnel B is re-established, multi-SIM communicationdevice then transmits data packets using both tunnel A and tunnel B. Inone variant, when the Scanning RF Unit has observed that received signalquality of the wireless connection between multi-SIM communicationdevice 101 a and base station 113 is worsening, multi-SIM communicationdevice 101 may not use tunnel B even though tunnel B is not broken inorder to reduce packet loss.

FIG. 5 is a flowchart illustrating the steps according to variousembodiments of the present invention. Multi-SIM communication devices101 a, 101 b and 101 c can be viewed in conjunction with FIG. 5respectively to illustrate how event triggers could be used to selectone of more SIM cards. Event triggers include but are not limited to ageographic location trigger, a data usage trigger, a received signalquality trigger, a time trigger, a duration of usage trigger, a billingcycle trigger etc. Event triggers may be referred to as a first eventtrigger and a second event trigger as illustrated in FIG. 5, step 501and 503 respectively. In one variant, a plurality of triggers can becombined to form an event trigger. For example, the first event triggercan be based on a geographic location trigger and a data usage trigger.In another example, the second event trigger can be based on theduration of usage trigger and the billing cycle information trigger. Inone variant, the first event trigger and the second event trigger can bebased on the same trigger(s).

Multi-SIM communication device has two SIM cards 291 a and 291 b, twoSIM card interfaces 292 a and 292 b, one processing unit 295, onestorage unit 295 and one RF unit 293 a. There are also two wirelesscommunication networks available where SIM 291 a is authorized for afirst wireless communication network, and SIM 291 b is authorized for asecond wireless communication network.

Multi-SIM communication device 101 c originally uses SIM card 291 a forillustration purpose only, as the first SIM card to establish a wirelesscommunication. At step 501, when a first event trigger has occurred, SIMcard 291 a cannot be used. The wireless connection established using SIMcard 291 a and RF unit 293 a may have been broken or terminated.

At step 502, multi-SIM communication device 101 c uses a second SIM cardto establish a wireless connection, which is SIM card 291 b in thisexample. After RF unit 293 a has disconnected from the establishedwireless connection with the first wireless communication network, itcan be used to establish another wireless connection with anotherwireless communication network as SIM 291 b is authorized to establishwireless connections with the second wireless communication network,therefore it is selected by processing unit 295 to be served by RF unit293 a through SIM card interface 292 b to establish a wirelessconnection with the second wireless communication network. As there aretwo SIM cards, SIM card 291 a and 291 b, SIM card 291 b is the only SIMcard that can be the second SIM card in step 502. If multi-SIMcommunication device 101 c has more SIM cards, one of SIM card 291 b andthe more SIM cards and can be selected to be the second SIM card in step502. The selection can be based on one or more criteria. For example,the least used SIM card is selected to be the second SIM card. Inanother example, the SIM card that has the corresponding lowest tariffprice is selected to be the second SIM card. In another example, the SIMcard that has the expected network performance is selected to be thesecond SIM card. In another example, each of the SIM card is assignedwith a priority and the selection is based on the priority. The prioritycan be entered by a user of multi-SIM communication device 101 c, themanufacturer of multi-SIM communication device 101 c, the position ofthe SIM sockets used to house the SIM cards, or retrieved from a remoteserver. The network performance may be determined by using resultsreported by a Scanning RF Unit.

At step 503, processing unit monitors for a second event trigger or isnotified by a second event trigger. The second event trigger may occurdue to but not limited to the following reasons: a duration of usage,conditions of the current connection, reaching the cap of a data usageplan, and geographical location. When the second event trigger does notoccur, processing unit 295 continues monitoring for the second eventtrigger and multi-SIM communication device 101 c continues using SIMcard 291 b. On the other hand, when the second event trigger occurs, forexample, after a duration of usage has been reached, processing unit 295will perform step 504.

One example for the second event trigger may be based on duration ofusage trigger. The duration of usage may be set by the vendor ofmulti-SIM communication device 101 c, a user of multi-SIM communicationdevice 101 c or retrieved from a remote server. One such purpose may bedue to a preference in the use of a specific wireless communicationnetwork. The user may specify that the second wireless communicationnetwork should only be used for sixty minutes per session. In onevariant, if multi-SIM communication device 101 c disconnects from thesecond wireless communication network, the sixty minute session ends andis restarted when another wireless connection is established with thesecond wireless communication network at a later time. After sixtyminutes has been reached, the second event trigger occurs and step 504is performed. Similarly, the first event trigger can also be based onthe duration of usage, for example, when the duration of usage has beenreached, the first event trigger occurs.

In another variant, it is known that while received signal quality maybe above the threshold, it is possible that data packets cannot betransmitted. There are many reasons for this but one example may be whenmulti-SIM terminal 101 c has already established a wireless connectionwith base station 111, but the connection between network controller andinterconnected networks 117 is slow. Processing unit 295 may use theobserved signal quality as a trigger, in conjunction with a networkperformance trigger. The network performance trigger may be based on thebandwidth and packet drop rate with network node 119. For example, ifthe wireless connection established with SIM 291 a has signal qualityabove the threshold but the network performance is below anotherthreshold, the second event trigger occurs. If the signal quality isabove a threshold and the network performance above the anotherthreshold, the second event trigger does not occur.

In another example, the second event trigger may be based on geographiclocation data. Geographic location data may include geographiccoordinate data based on the geographic coordinate system. Thegeographic location data may be received by the RF unit such as RF unit293 a. It may also be received by an embedded or external GPS receiverwhich is not illustrated in FIG. 2C. The geographic location data may bepredefined as a trigger. This may be set by the vendor of multi-SIMcommunication device 101 c, the user of multi-SIM communication device101 c or the data may be retrieved from a remote server. For example, ispossible to locate multi-SIM communication device 101 c on a map inreal-time as it receives geographic location data. Similarly, the firstevent trigger can also be based on geographic location data, for examplewhen the geographic location is known to be without of the coverage areaof a wireless communication network, the first event trigger occurs. Onescenario where this may be used is when the multi-SIM communicationdevice is without the coverage area of a wireless communication network.In order to continue transmitting data and not incur wirelesscommunication network roaming charges or to incur charges from anotherwireless communication network with a higher tariff pricing, the secondevent trigger occurs as soon as its geographic location data matches thepredefined geographic location trigger. For example, the predefinedthreshold is a location fence for geographic location A. The geographiclocation data received by multi-SIM communication device 101 c isdetermined by processing unit 295 to be above the threshold when it isoutside of the geographic location A and therefore the second eventtrigger occurs so that multi-SIM communication device 101 c may selectanother operational SIM card.

In one example, the second event trigger is based on tariff pricinginformation. The tariff pricing information typically includes at leastthe monthly cellular subscription cost, the monthly data usage limit,the premium for exceeding the monthly data usage limit, and the premiumfor using a roaming network. The tariff pricing information may beinputted by a user or retrieved from a remote server, and then stored instorage unit 296 for later retrieval. For illustration purpose only,when processing unit 295 has determined that the tariff price of thesecond SIM card, which is SIM card 291 b, is not the cheapest, a secondevent trigger occurs. Those who are skilled in the art would appreciatethat there are myriad of reasons why the tariff price of SIM card 291 bis not the cheapest. Similarly, the first event trigger can also bebased on tariff pricing information, for example when the tariff priceof SIM card 291 a is no longer the cheapest, the first event triggeroccurs.

In one variant, processing unit 295 monitors tariff pricing informationfrom network operators corresponding to SIM cards 291 a and 291 b as itis possible that network operators may change tariff prices. Those whoare skilled in the art would appreciate that there are myriad of reasonswhy network operators change tariff prices. For example, due tocongested network environment, a network operator may increase thetariff price in real-time. When processing unit 295 has discovered thatthe tariff price of the SIM card 291 b is not the cheapest, the secondevent trigger occurs.

In another variant, the second trigger occurs based on both the tariffpricing information and the data usage for both SIM cards 291 a and 291b. For example, network operators may have different tariff prices basedon data usage especially after the data usage limit has been reached.When processing unit 295 determines that SIM card 291 b is no longer thecheapest based on data usage, the second event trigger occurs.

In another example, the second event trigger may be based on the billingcycle information. A billing cycle is when the period of a cellularsubscription for communication service, usually monthly. It is commonthat once a billing cycle ends, the data usage counter ceases for themonth and a new billing cycle begins. Similarly, the first event triggercan also be based on the billing cycle information. For example, whenthe billing cycle is about to end, the first event trigger occurs.

The billing cycle period may be set by the vendor of multi-SIMcommunication device 101 c, a user of multi-SIM communication device 101c or the trigger data may be retrieved from a remote server. Onescenario where this may be used is when data traffic per month is cappedand a balanced data usage across two SIM cards may be desirable. For thepurpose of illustration, the first wireless communication network andsecond wireless communication network each allows for one gigabyte ofdata to be transmitted per month and data exceeding the allowance ischarged at a high premium. The billing cycle of the first wirelesscommunication network is from the first day to the last day of everymonth and the billing cycle of the second wireless communication networkis from the fourteenth day of the current month to the fourteenth day ofthe next month. The user estimates that SIM 291 a would be nearing itsdata usage allowance by the end of the month and hence sets a higherpriority based on usage for the second wireless communication networkwhen it is near the end of the month. Similarly, the user sets a higherpriority based on usage for the first wireless communication networknear the middle of the month as he estimates that SIM 291 b would benearing its data usage allowance by the middle of the month, when itsbilling cycle is nearing its end. Therefore, the second event triggeroccurs near the end of the month and multi-SIM communication device 101c attempts to use SIM 291 b. Similarly, the second event trigger occursnear the middle of the month and multi-SIM communication device 101 cattempts to use SIM 291 a. In one variant, the user sets the billingcycle as above, as well as sets communication network priority based ondata usage according to the billing cycle. So while SIM 291 b has higherpriority based on usage near the end of a month, if the data usage onthe second wireless communication network is already nearing onegigabyte which is the limit in this illustration, SIM 291 a may beselected for use.

In another example, processing unit 295 may receive the second eventtrigger from RF unit 293 a when the observed signal quality is below athreshold. For the purpose of illustration, RF unit 293 a is capable ofactivating the second event trigger when it has determined that thesignal quality has fallen to less than the threshold. One example of thethreshold is −100 dB. Similarly, the first event trigger can also bebased on the observed signal quality. For example, when the observedsignal quality is below a threshold, the first event trigger occurs.

In another example, processing unit 295 receives the second eventtrigger which is based on geographic location data from the operatingsystem, processing unit 295 then collects signal quality data from RFunit 293 a and stores both sets of data to storage unit 296. For thepurpose of illustration, processing unit 295 combines both sets of dataover a period of time, creating a record of different geographic areaand their prevailing signal quality. With this information, multi-SIMcommunication device 101 c may be able to anticipate areas where thesignal quality is below a threshold and activate the second eventtrigger in order to use another wireless communication network.

Another example for the second event trigger may be based on a timetrigger. The time trigger may be set by the vendor of multi-SIMcommunication device 101 c, the user of multi-SIM communication device101 c, retrieved from a remote server or retrieved internally from themulti-SIM communication device. The user may set for the second triggerto occur based on time. There are many reasons why this may be used butone example may be when the second network operator sets its tariffprices to be more expensive between certain time of the day. The usermay set the time trigger to occur at a specific time for SIM 292 b, whenSIM 292 b was used by RF unit 293 a to establish a wireless connectionswith the second communication network. Similarly, the first eventtrigger also be based on the time trigger, for example, when a specifiedtime of the day has been reached, the first event trigger occurs.

In one embodiment of the present invention, a trigger monitor isimplemented into multi-SIM terminal 101. The trigger monitor monitorsfor how frequent the SIM cards are being selected based on a predefinedtime period. There are many reasons for why the SIM cards are beingselected frequently such as when the first and second event triggers areoccurring frequently. For example, when a SIM card such as SIM card 291a from FIG. 2C is no longer operational, the first event trigger occursas step 501. A second SIM card such as SIM card 291 b is used in step502. When SIM card 291 b is no longer operational, the second eventtrigger occurs at step 503. At step 504, an operational SIM card may beSIM 291 a, SIM 291 b or another SIM card. When the selected operationSIM card is no longer operational again, the first event trigger mayoccur again, leading to the second event trigger and so on. The reasonwhy the SIM card may no longer be operational could be due but notlimited to failure of the wireless communication networks, failure ofthe SIM card, being outside of the coverage area of any base stationetc. When the SIM card selection frequency reaches a threshold and aspecified period of time has lapsed, the processing unit may apply atime delay to one or both event triggers so that the performance of step504 is delayed. If after another predefined period of time, thefrequency of SIM card selection still has the characteristics of forexample, a SIM card failure, processing unit may instruct the RF unitsto perform an action such as power-cycle, enter sleep mode, enter a lowpower mode etc. The purpose of this implementation is to minimize thechance of the first and the second event trigger from occurringrepeatedly.

After the second event trigger has occurred, step 504 is performed byprocessing unit 295 to select an operational SIM card. The operationalSIM card can be the first SIM card, the second SIM card or another SIMcard. As there is no SIM card other than SIM cards 291 a and 291 b inthis example, there is no another SIM card. If there are other SIM cardsother than SIM cards 291 a and 291 b in multi-SIM communication device101 c, the other SIM cards can be the another SIM card. After a SIM cardis selected to be the operational SIM card, processing unit 295 can usethe operational SIM card to establish a wireless connection. There canbe no SIM card selected to be the operational SIM card and result in nowireless connection being able to be established.

In one variant, after step 504, processing unit 295 will go back to step501 when the first event trigger is triggered. This allows the first SIMcard be used again in case the first event trigger is triggered. Forexample, the operational SIM card is SIM card.

FIG. 6 illustrates processes according to one of embodiments of thepresent invention that an operational SIM card can be selected in step504. There is no limitation that the processes of FIG. 6 are the onlyprocesses to perform step 504.

At step 601, processing unit 295 determines the list of SIM cards thatcan be used as the operational SIM card. As multi-SIM communicationdevice 101 c has SIM cards 291 a and 291 b, the list of SIM cards isconsisted of SIM cards 291 a and 291 b. If one of the SIM cards 291 aand 291 b is removed, the removed SIM card is not in the list of SIMcards. If a multi-SIM communication device has ten SIM cards, the listof SIM cards is consisted of the ten SIM cards. In one variant, SIMcards that can be included in the list of SIM cards are subject to oneor more rules. For example, a rule can be that the second SIM card,which is SIM 291 b in this embodiment, cannot be in the list of SIMcards as the conditions for triggering the second event trigger maystill apply. In another example, SIM card(s) that is(are) being used byother RF unit(s) cannot be in the list of SIM cards as the SIM card(s)has(have) already being used. The rule can be entered by a user of themulti-SIM communication device, the manufacturer of the multi-SIMcommunication device or retrieved from a remote server.

At step 602, processing unit 295 select a SIM card from the list of SIMcards. Multi-SIM communication device 101 c, for illustration purposeonly, selects SIM card 291 a. The selection can be based on one or morecriteria. For example, the SIM card that has the lowest price tariff isselected. In another example, the SIM card that may have the bestnetwork performance is selected. The network performance may bedetermined by using results reported by a Scanning RF Unit. In onevariant, the one or more criteria at step 602 may be the same as the oneor more criteria at step 502.

At step 603, if there is no SIM card can be selected, the selectionprocess stops at step 607 that no operational SIM card is selected. Whenall the SIM cards in the list of SIM cards have been used to establishcorresponding wireless connections at step 604 and no wirelessconnection can be established at 605, there will be no further SIM cardin the list of SIM cards can be selected at step 602 and results in nooperational SIM card is selected.

At step 604, the selected SIM card is used to establish a wirelessconnection. For example, selected SIM card at step 603 is SIM card 291a, then processing unit 295 tries to use RF unit 293 a and SIM card 291a to establish a wireless connection. If a wireless connection can beestablished, this indicates that the SIM card selected, i.e. SIM card291 a in this example, can be the operational SIM card at step 606. Ifno wireless connection can be established, then step 602 will beperformed to select another SIM card from the list of SIM cards. Thereare myriads reasons why a wireless connection cannot be established. Forexample, multi-SIM communication device 101 c is out of the coveragearea of the network of the network operator corresponding to SIM card291 a or the quota of SIM card 291 a is used up.

In one embodiment, multi-SIM communication device 101 a may apply theprocesses in FIG. 5 and FIG. 6 to RF unit 221 b and SIM cards 201 b and201 c that RF unit 221 b are capable of connecting to through SIM cardinterfaces 221 b and 211 c respectively. However, multi-SIMcommunication device 101 a does not apply the processes in FIG. 5 andFIG. 6 to RF unit 221 a and SIM cards 201 a as RF unit 221 a is onlyaccessible to SIM card 201 a. For illustration purpose only, in thisembodiment, SIM card 201 b is the first SIM card and SIM card 201 c isthe second SIM card. In one variant, RF unit 221 a can be used as aScanning RF Unit to provide received signal qualify information forprocessing unit 231 to select operational SIM card at step 502 and/orstep 504 when received signal qualify is a criteria for step 502 and/orstep 504. In one variant, RF unit 221 a is not used as a Scanning RFUnit and instead is used to establish a wireless connection. This allowstwo wireless connections established at multi-SIM communication device101 a.

In one embodiment, multi-SIM communication device 101 a may apply theprocesses in FIG. 5 and FIG. 6 to SIM cards 201 a, 201 b and 201 c. Forillustration purpose only, in this embodiment, SIM card 201 a is thefirst SIM card and SIM card 201 b is the second SIM card. When SIM card201 a is used, RF unit 221 a is used to establish a wireless connectionwhile RF unit 221 b is not used to establish a wireless connection or isused as a Scanning RF Unit. When SIM card 201 b used at step 502, RFunit 221 b is used to establish a wireless connection while RF unit 221a is not used to establish a wireless connection or is used as aScanning RF Unit. Therefore, only one of SIM cards 201 a, 201 b and 201c is used to establish a wireless connection and other two SIM cards canbe used as backups.

In one embodiment, multi-SIM communication device 101 a may apply theprocesses in FIG. 5 and FIG. 6 to SIM cards 201 a, 201 b and 201 c. Forillustration purpose only, in this embodiment, SIM card 201 b is thefirst SIM card, SIM card 201 a is the second SIM card and operationalSIM card can be selected from SIM card 201 b or SIM card 201 c. Thisallows SIM card 201 a to be used quickly when SIM card 201 b is not useddue to the first event trigger. This also allows processing unit 295 tohave adequate time to determine whether to use SIM cards 201 b or 201 cas the operational SIM card as only one of SIM cards 201 b and 201 c canbe used by RF unit 221 b at any moment to establish a wirelessconnection.

In one variant, RF unit 221 a can be used as a Scanning RF Unit toprovide received signal qualify information for processing unit 231 toselect operational SIM card at step 502 and/or step 504 when receivedsignal qualify is a criteria for step 502 and/or step 504.

In one embodiment, multi-SIM communication device 101 b may apply theprocesses in FIG. 5 and FIG. 6 to RF units 271 a and 271 b and SIM cards251 a, 251 b and 251 c that RF units 271 a and 271 b are capable ofconnecting to through SIM card interface selector 284, and then SIM cardinterfaces 261 a, 261 b and 261 c respectively. When processing unit 281selects SIM cards for use as the first SIM card, the second SIM card andthe operational SIM card, processing unit 281 can instruct SIM cardinterface selector 284 to select one of SIM cards 251 a, 251 b and 251 cfor RF units 271 a or 271 b. In one example, SIM cards 251 a is thefirst SIM card and the operational SIM card; SIM card 251 b is thesecond SIM card and SIM card 251 c is used for a Scanning RF unit toallow frequent observation of received signal quality.

In one variant, multi-SIM communication device 101 b is configured insuch a way where RF unit 271 a is able to use SIM cards 251 a and 251 bas the first SIM card, the second SIM card and the operational SIM card.RF unit 271 b is able to use SIM card 261 c only. When processing unit281 selects SIM cards 251 a and 251 b to the first SIM card, the secondSIM card and the operational SIM card, processing unit 281 can instructSIM card interface selector 284 to perform the selection. Therefore,multi-SIM communication device 101 b is capable of establishing twowireless connections. A plurality of tunnels can be established in thetwo wireless connections. Data packets can be transmitted and receivedthrough the plurality of tunnels. Further, the plurality of tunnels canbe aggregated to form one aggregated VPN connection.

There is no limitation for number of RF units in a multi-SIMcommunication device for the present invention. The number of SIM cardsis at least two. It is preferred to have more SIM cards and RF units asa RF unit needs at least one SIM card in order to establish a wirelessconnection.

The invention claimed is:
 1. A method to wirelessly connect to at leastone base station at a multi-SIM communication device, wherein themulti-SIM communication device comprises a plurality of SIM cardinterfaces and a plurality of RF units, comprising the steps of:scanning for base stations using a first RF unit; observing receivedsignal quality using the first RF unit; transmitting data packets basedin part on the received signal quality through at least one of theplurality of RF units; selecting a first base station based in part onthe received quality for the first base station; when a second RF unitis not available, making the second RF unit available by disconnecting awireless connection that the second RF unit has established;establishing a wireless connection with the first base station using thesecond RF unit before performing the step of transmitting data packets;wherein the received signal quality for the first base station is abovea threshold; and wherein the second RF unit is one of the at least oneof the plurality of RF units.
 2. According to the method of claim 1,wherein the step of observing is performed according to the receivedsignal quality.
 3. According to the method of claim 1, wherein each ofthe plurality of RF units is connected to at least one SIM cardinterface.
 4. According to the method of claim 1, further comprising:establishing a wireless connection with a second base station using thesecond RF unit before performing the step of transmitting data packetsif the first base station is unable to be connected to; and whereinreceived signal quality for the second base station is above thethreshold.
 5. According to the method of claim 1, further comprising:selecting a third base station based in part on the received signalquality for the third base station; establishing a wireless connectionwith the third base station using a third RF unit before performing thestep of transmitting data packets; wherein the received signal qualityfor the three base station is above a threshold; wherein the third RFunit is one of the plurality of RF units; and wherein the third RF unitis not the same as the second RF unit.
 6. According to the method ofclaim 3, wherein each of the plurality of RF units is connected to aplurality of SIM card interfaces through a SIM card interface selector.7. According to the method of claim 5, further comprising: establishinga first tunnel through the wireless connection established with thefirst base station; establishing a second tunnel through the wirelessconnection established with the first base station; wherein the datapackets are transmitted through the first tunnel and the second tunnel;and wherein the first tunnel and the second tunnel are aggregatedtogether to form an aggregated connection.
 8. According to the method ofclaim 7, further comprising: when received signal quality with a basestation is worsening, corresponding tunnel is not used even though thecorresponding tunnel is not broken; wherein the base station is one ofthe first station and the second station; wherein the correspondingtunnel is the tunnel established between a RF unit with the basestation; and wherein the RF unit is one of the first RF unit and thesecond RF unit.
 9. A multi-SIM communication device capable ofwirelessly connecting at least one base station, the multi-SIM devicecomprising: a plurality of SIM card interfaces; a plurality of RF units;at least one network interface; at least one processing unit; at leastone memory; at least one storage unit storing program instructionsexecutable by the at least one processing unit for: scanning for basestations using a first RF unit; observing received signal quality usingthe first RF unit; transmitting data packets based in part on thereceived signal quality through at least one of the plurality of RFunits; selecting a first base station based in part on the receivedsignal quality for the first base station; when a second RF unitavailable, making the second RF unit available by disconnecting awireless connection that the second RF unit has established;establishing a wireless connection with the first base station using thesecond RF unit before performing the step of transmitting data packets;wherein the received signal quality for the first base station is abovea threshold; and wherein the second RF unit is one of the at least oneof the plurality of RF units.
 10. The multi-SIM communication device ofclaim 9, wherein the step of observing is performed according to thereceived signal quality.
 11. The multi-SIM communication device of claim9, wherein each of the plurality of RF units is connected to at leastone SIM card interface.
 12. The multi-SIM communication device of claim9, wherein each of the plurality of RF units is connected to a pluralityof SIM card interfaces through a SIM card interface selector.
 13. Themulti-SIM communication device of claim 9, wherein the at least onestorage unit further storing program instructions executable by the atleast one processing unit for: establishing a wireless connection with asecond base station using the second RF unit before performing the stepof transmitting data packets if the first base station is unable to beconnected to; and wherein received signal quality for the second basestation is above the threshold.
 14. The multi-SIM communication deviceof claim 9, wherein the at least one storage unit further storingprogram instructions executable by the at least one processing unit for:selecting a third base station based in part on the received signalquality for the third base station; establishing, a wireless connectionwith the third base station using a third RF unit before performing thestep of transmitting data packets; wherein the received signal qualityfor the three base station is above a threshold; wherein the third RFunit is one of the plurality of RF units; wherein the third RF unit canbe the same or different from the first RF unit; and wherein the thirdRF unit is not the same as the second RF unit.
 15. The multi-SIMcommunication device of claim 14, wherein the at least one storage unitfurther storing program instructions executable by the at least oneprocessing unit for: establishing a first tunnel through the wirelessconnection established with the first base station; establishing asecond tunnel through the wireless connection established with the firstbase station; wherein the data packets are transmitted through the firsttunnel and the second tunnel; and wherein the first tunnel and thesecond tunnel are aggregated together to form an aggregated connection.16. The multi-SIM communication device of claim 15, further comprising:when received signal quality with a base station is worsening,corresponding tunnel is not used even though the corresponding tunnel isnot broken; wherein the base station is one of the first station and thesecond station; wherein the corresponding tunnel is the tunnelestablished between a RF unit with the base station; and wherein the RFunit is one of the first RF unit and the second RF unit.